A control method and control system for uninterrupted operation of a hybrid mmc

Abstract

The invention discloses a control method and a control system for uninterrupted operation of a hybrid MMC. The control method includes: obtaining the reference value of the AC output voltage of the upper and lower bridge arms of each phase, obtaining the reference value of the DC voltage, and obtaining the reference value of the upper and lower bridge arms of each phase. Arm negative-sequence double-frequency circulating current suppression reference voltage, obtain the reference value of the zero-sequence circulating current compensation potential of the upper and lower bridge arms of each phase, and generate a drive signal. The control system includes an AC current control device, a DC current control device, a negative-sequence circulating current suppression control device, a zero-sequence circulating current suppression control device, and a drive signal synthesis device, which are used to obtain the reference values ​​of the AC output voltage of the upper and lower bridge arms of each phase, and the DC Voltage reference value, negative-sequence double-frequency circulating current suppression reference voltage of upper and lower bridge arms of each phase, zero-sequence circulating current compensation potential reference value of upper and lower bridge arms of each phase, and drive signals. The invention can uniformly control the AC positive and negative sequence currents, suppress the AC negative sequence current and the zero-sequence circulating current of the bridge arm, control the DC side current, and finally realize uninterrupted operation.

Description

technical field [0001] The invention belongs to the technical field of power transmission and distribution of electric power systems, and more specifically relates to a control method for uninterrupted operation of a hybrid MMC for AC asymmetric faults and DC faults. Background technique [0002] Modular multilevel converter (MMC) has the advantages of modular structure and easy expansion, and has been widely used in the field of flexible direct current transmission. Among various MMC topologies, the hybrid MMC based on Full bridge sub-module (FBSM) and Half bridge sub-module (HBSM) has good control characteristics. 1. The DC decoupling control method, which can not block the switching device IGBT and ride through the DC fault when the DC fault occurs, is a scheme with application prospects. [0003] At present, the modeling and control strategies of the hybrid MMC are based on the three-phase symmetrical power grid, and the probability of asymmetrical faults in the AC powe...

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Problems solved by technology

[0004] However, the above-mentioned solutions only control the electrical quantity on the AC side, and the control structure has defects, so it cannot control the electrical quantity on the DC side; moreover, none of the above-mentioned solutions has the ability to handle DC faults, and cannot guarantee that the hybrid MMC will operate in the AC side. Uninterrupted operation during symmetrical and DC faults

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